Locking means for fluid motors



Oct. 21, 1941. L. w. GREVE LOCKING MEANS FOR FLUID MOTORS Filed May 7, 1958 M PR 5 mm w W I.

ATTORNEY Patented Oet. 21, 1941 2,259,815 LOCKING MEANS FOR FLUID MOTORS Louis W. Greve, Cleveland, Ohio, assigns: to The leveiand land, Ohio,

Pneumatic Tool Company, Clevea corporation of Ohio Application May 7, 1938, Serial No. 206,620

Claims.

This invention relates broadly to fluid motors, but more particularly to the type of fluid motor used for retracting and lowering the landing gear of airplanes and the like.

One object of this invention is to produce a fluid actuated motor including a pair of telescoping cylindrical members, with means for automatically locking the motor against accidental expansion in the event of a i'ailure of the motive fluid within the motor.

Another object of this invention is the production of a fluid actuated motor equipped with a locking device located within the motor and forming a compact and light assembly which is strong, durable and eflicient.

In the drawing:

Fig. l is a side elevatio view partly in section of a fluid motor embodying the invention and shown in extended position.

Fig. 2 is a view similar to Fig. 1, showing the motor in a retracted position.

Fig. 3 is a cross sectional view taken in a plane indicated by line 3-3 in Fig. 1.

Fig. 4 is a fragmental side elevational view of a fluid motor shown partly in section and illustrating a modification of the invention.

Referring to the drawing in which like symbols designate corresponding parts throughout the several views, I5 represents an outer cylinder having its upper end closed by an integral head It formed with a clevis I! for connection to the fuselage of an airplane. The head It is provided with a threaded connection or passage it through which motive fluid may be admitted into the upper end of the cylinder I5.

Screwed on the lower end of the cylinder ii. there is a bearing member It also provided with a passage 20 for admitting motive fluid into the lower end of the cylinder I5, and carrying packings 2i held in position by an adjustable gland nut 22.

Telescopically mounted within the outer cylinder I8, there is an inner cylindrical member 21 having its lower end portion protruding therefrom and terminated by a connection 24 through which the inner member 23 may be secured to the landing gear of the airplane. The other end portion of the inner member 23 carries a piston 25 and a cup-shaped resilient washer 28 secured in position by a nut 21 and mounted within the outer cylinder for slidable fluidtight engagement with the inner wall thereof.

Referring now more particularly to the invention, 28 represents an extension of the inner member 23 having a tapered peripheral wall 3|, there is a compression 20 leading inwardly toward the piston 2! and surrounded by the side wall III of a cup-shaped auxiliary piston 3|, which carries a cup-shaped resilient washer 32 held in position by a nut 88. Extending radially throush the side wall ll of the auxiliary piston ll, there are four equally spaced rectangular orifices 34 each having a brake shoe 3! radially slidable therein. The inner wall It of each shoe is laterally concaved and longitudinally tapered to flt on the tapered peripheral wall is of the extension 28, while the outer end wall 31 of each shoe is laterally convexed and longitudinally straight to flt against the inner wall of the cylinder IS. The shoes 35 are of an equal length calculated to enable limited axial movement of the auxiliary piston II relative to the extension 28. Interposed between the extension 28 and the auxiliary piston spring 38 constantly urging the piston 3i away from the extension 28.

In the modification shown in Fig. 4, the piston I25 and its component cup-shaped resilient washer I28 are detachably secured on the inner cylindrical member I23 by a nut I21. In this construction the auxiliary piston It! includes a sleeve 89 having its upper end internally threaded to receive a plug Iii by which the cup-shaped resilient washer I32 is secured to the piston III. The inner wall I 38 of the sleeve is tapered to fit on the tapered peripheral wall I28 of the extension I28, while its outer wall I3! is cylindrical to flt on the inner wall of the outer cylinder III. To enable expansion or the sleeve, it is provided with a plurality of longitudinal slots II leading upwardly from the lower end thereof and each terminated by a hole I! extending radially through the upper end portion of the sleeve which is reduced in cross section by an inner annular groove 0. Interposed between the auxiliary piston Ill and the extension I28, there is also a compression spring I38.

In practice. to the connecting passages I8 and 20 are attached motive fluid conveying conduits admitting motive fluid into the cylinder I5. These conduits are controlled by a suitable valve whereby motive fluid is admitted into the cylinder it through one passage and free to exhaust through the other. For the purpose of explanation, let it be assumed that the motor is in extended position as shown in Fig. l and that motive fluid is admitted into the cylinder I! through the passage III while the passage I8 is open to exhaust. In this instance, the motive fluid acting on the piston 25 through its component cup-shaped resilient washer 18, will ef- 2 a,aso,e1s (act the fluidtight engagement of this washer resilient washer m to effect its fluid tight enwith the inner wall of the cylinder IS. The mogagement with the inner wall of the cylinder Ill, tive iluid acting on the piston will also cause and drive the auxiliary piston iii until the plug the upward telescopic movement of the inner Ill engages the upper end of the extension III. member 23 resulting in the contraction of the 5 This downward movement or the auxiliary piston motor. During this upward movement, the com- Ill and sleeve Ill relative to the extension ill. pression spring 3! acting on the auxiliary piswill cause the inner wall I36 01 the sleeve to be ton 3| will maintain it away from the extension moved out of engagement with the tapered pea as shown in Fig. 3. in which instance furripheral wall I" of the extension I28, thereby ther axial movement of the piston 3| away from relieving the sleeve from its frictional locking the extension 28 is prevented bythe engagement engagement with the inner wall at the cylinder of the brake shoes I! with the peripheral wall HI, and enabling the free downward telescopic of the extension 28 and the inner wall of the movement of the inner cylinder I23. cylinder II. The tension of the spring I8 is In the modified construction above referred calculated to cause only a slight radial thrust of 15 thereto. it will be understood that the radial the shoes 35 on the inner wall of the cylinder thrust resulting from the expansion of the sleeve II, which radial thrust does not materially afll is acting practically on the entire peripheral feet the free telescopic movement of the inner inner wall of the cylinder H5, enabling the sleeve member II. to be made of metal having a smaller coefllcicnt After theinner member 28 has been moved go of friction than that of the brake shoes 35, withupwardly within the cylinder II, its return stroke out affecting the locking emoiency of the sleeve. eflecting the expansion of the motor by any In practice, this sleeve is preferably made of forces other than that of the motive fluid adsofter metal than that of the cylinder Hi, theremitted into the cylinder lb'through the passage by preventing any possible scoring or scratchin II, is prevented by the locking mechanism inof the inner wall of the cylinder. cluding the shoes 35. For instance when the Although the foregoing description is necesinner member 23 is subjected to an axial pull sarily of a detailed character, in order to comtending to eflect the expansion of the motor, pletely set forth the invention it is to be underthe extension 28 will tend to move away from stood that the specific terminology is not intended the auxiliary piston 3|, causing a wedging ac- 30 to be restrictive or confining and it is to be turtion between the taper wall 29 and the shoes ther understood that various rearrangements of eil'ecting the radial thrust of the shoes against parts and modifications of structural detail may the inner wall of the cylinder II, which thrust be resorted to without departing from the scope is suillcient to prevent the outward slidable moveor spirit of the invention as herein claimed. merit of the inner member 23. The extent of 35 Iclaim: the radial thrust oi the shoes 35 against the 1. In a device of the character described, a inner wall of the cylinder II is proportional to pair of telescoping cylindrical members, passages the extent of the axial pull to which the inner admitting motive fluid into the outer member for member 23 may be subjected, thereby preventefiecting the telescopic movement of said meming any noticeable expansion of the motor ir- 40 bers, a sleeve between said members capable oi respective of the load carried by the inner memexpansion into frictional locking engagement her a. with said outer member. and interengaging When it is desired to eiIect the expansion of means on said sleeve and inner member autothe motor. e mo i e flu y be admitted into matically effecting the expansion of the sleeve the upper end of the cylinder l5 t ug t e upon initial movement of said inner member in connection It, while the connection 20 is opened one direction by pulling forces t which said to exhaust. In this instance, the motive fluid inner member may be subj ct d will first act on the cup-shaped resilient washer 2, In a device of t character described, an 32 to effect its fluid g t engagement with the outer cylindrical member formed with a subinner wall of the Outer cy The motive so stantially smooth inner wall, an inner cylindrical flui acti on the u i y piston ll will drive member slidable within said outer member, pasand maintain it in the release position relative to sages adlnjttlng ti fluid 1 1. said outer the shoes 35. In ot er Words. th 91 p bar for eflecting the slidable movement of said TDD 1 w be moved from the Position Shown inner member, a brake carried by the inner mem- 3 t0 the Position shown in thel'eby on her including a sleeve capable of expansion into 084151118 the 8119-1 movement of the locking shoes frictional engagement with the inner Wall of the 35 f o a Operative Position 111150 in hmpelative outer member for preventing said slidable moveposit on relative to the t l p s cylindrical merit in one direction, and means included in said members and With the auxiliary Piston brake automatically eflectlng the expansion of II en a in the pp end the extension said sleeve upon movement of said inner memthe action 01 the mimve mud on the auxiliary bet in said one direction by forces other than that piston Ii is transmitted to the inner member 23 o! the motive fluid admitted into said outer for effecting its outward movement resulting in member. the expansion of the motor.

In the modified construction shown in Fm 4, 3. In a device of the character described, a

. pair of telescoping cylindrical members, passages a. pull exerted on the inner member ill will. dmmm t1 mud to th due to the engagement of the tapered mating sur- 8 mo V6 in 8 Outer membel faces I28 and I36. cause the expansion of the e ting the teleswpmg mwemem said sleeve 39 and the consequential frictional enan exp'msible sleeve between said members gagement or the sleeve's, outer wall "1 with the movable into friction creating position therebethe cylinder Hi, thereby preventtelescopic movement of the inner when the motive fluid is admitted of the cylinder HI through it will act on the cup-shaped inner wall of la outward member I23. into the upper end the connection, I it,

tween for preventing the telescoping movement of the inner member in one direction, and a wedge on said member automatically moving said sleeve into friction creating position upon initial movement of said inner member in said one dihaving one end rection by forces other than that oi the motive fluid aforesaid.

4. In a device of the character described, a cylindrical housing, a member within said housing having one end projecting therefrom, said housing and member being capable of relative slidable movement, asleeve carried by said member capable oi expansion into frictional locking engagement with the inner wall or said housing for preventing the slidable movement or said member in one direction, and means operatively associated with said sleeve automatically eil'ecting the expansion thereof upon initial movement 01 said member in said one direction by pulling forces to which said member may be subjected.

5. In a device of the character described, a cylindrical housing, a member within said housprojecting therefrom, said housing and member being capable of relative slidable movement, a main and an auxiliary piston on said member the former stationary thereon and the latter capable oi limited axial movement relative thereto,- passages through said housing for admitting motive fluid to one or the other of said pistons for eiiecting said relative slidable movement, an expansible sleeve carried by said auxiliary piston capable oi frictional engagement with said housing for preventing slidable movement in one direction of said member relative to said housing, and a wedge on said member efl'ecting the operative engagement of said sleeve upon axial movement of said member in one direction relative to said auxiliary piston.

LOUIS W. GREVE. 

